08 - STP - Rapid Spanning Tree Concepts and Configuration
portfast - on the host links interface range <ports>
spanning-tree port fast
To enable RSTP
spaning-tree mode rapid-pvst - do this on all the switches participating
Im going to uplug the uplink between Switch B and A, we should see the port change from altn/BLK to FWD straight away
9 - EtherChannel - Aggregating Redundant Links
Can bundle upto 8 ports
You get aggregated bandwidth, no wasted bandwidth, also load-balancing
Automatic failover if one of the links fails.
Its logical too, so this simplifies the management (apply config to etherchannel not the ports)
PAGP: If both auto, it wont be an etherchannel, one side has to be in desirable state.
best way to hard code both to ON
Only difference between the modes, well mainly the PAGP is cisco propietary and was invented first before a industry standard was around! Cisco kept it on and now you have a choice ... BUT obviously PAGP is cisco kit only.
L2 etherchannel
simple bundling of ports, Layer 2 domain
L3 etherchannel
you can put all ports in layer2, but assign them to a port channel interface, so you could have routing between your distribution layer and core layer, it allows for very fast convergence at the access layer! which some people are doing now. have routing at all layers.
Lets start with the Layer 2 etherchannel first:
config wise, just going with something simple, i have chosen PAGP:
inter range fas 0/23 - 24
channel-protocol pagp
channel-group 1 mode desirable
Modes shown here:
Once configured on both sides, a neat command is show etherchannel detail - handy nice layout of information (bonus of showing load of port-channel too)
Building upon the original configuration:
Need to remove the port-channel as we have negotiated a Layer 2 Etherchannel and it would of not allowed us to apply the switchport first.
inter range fas 0/23 - 24
no channel-group 1
no switchport <--- Enable layer3
channel-group 1 mode desirable
interface port-channel 1
no switchport <--- Enable layer3
ip address 10.1.1.1 255.255.255.0
The last point does not affect the port-channel! only the port .... so if you apply config moving it in a different VLAN etc it will be dropped from the bundle.
10 - L3 Switching - InterVLAN Routing Extraordinaire
*didnt doc this as its pretty basic and i know it inside out,
Okay and i can ping from both hosts to both the respective vlans/SVI's
Lets look at the next part:
So we can turn fa0/24 into a routed port! lets do that:
10.1.24.2 is the router the other end of the link, the router is also running EIGRP, lets enable THAT TOOO.
We have an EIGRP neighbour, lets check the routing table
How kool is that! we have "SWOUTER" lol! SWEEET!
Dont ask about the diagram, if your have seen the CBT nugget your'll get it lol:
Packet goes to the router, so once the first packet has been to the router, all future
packets go to the hardware part of the switch (ASIC)/CEF and they just fly by!
Layer3 vs Multilayer switching
L3 = switch has a router in it
multilayer = has ability to cache route info (CEF)
every L3 switch is a multilayer switch
however not every multilayer switch is a L3 switch
